On the ProDevTips.com site today there's a new tutorial showing how to create a simple CRUD (create, read, update, delete) interface to your database tables with PHP and jQuery (here's an example).
I recently made a very simple but functional administrational interface using jQuery and Ajax to avoid having to refresh the page all the time thus simplifying development.The only convention/requirement here is that any database table that uses the interface has a unique id column aptly named id.
Their example is pretty simple - it lets you view the contents of the cells, allows you to change their values in the form fields (or delete the record) and save the changes. Complete code - HTML, PHP and jQuery - is included.